Cutaneous metastasis (CM) occurs in 20% of patients with breast carcinoma (BCA), and is extremely difficult to treat. These CM are relatively resistant to chemotherapy, generally responding only to ionizing radiation (IR). Multiple rounds of IR, however, lead to debilitating fibrosis and radiation dermatitis. An alternative to IR is needed for better management of BCA/CM. In our laboratory, we have developed differentiation-enhanced combination PDT (cPDT), a concept in which a pro-differentiating agent (methotrexate; vitamin D; or 5-fluorouracil, 5FU) is used as a neoadjuvant prior to PDT. After using these neoadjuvants, levels of protoporphyrin IX (PpIX) were elevated in animal tumor models of skin, prostate, and BCA, leading to better PDT efficacy. However, all the agents have toxicity issues. Here, we use a nontoxic 5FU precursor called Capecitabine (CPBN) for cPDT. CBPN is a standard chemotherapeutic for metastatic BCA, and is metabolized to 5FU specifically within tumor tissue. Murine (4T1) and human (MCF-7) BCA cell lines were injected into breast fat pads of nude mice. After tumor nodules appeared, CPBN (400-600 mg/kg/day) was administered by oral gavage for five days followed by intraperitoneal ALA administration on day 6. Mice were sacrificed and tumors harvested. CPBN pretreatment led to a 4-fold elevation of PpIX levels in tumors, relative to vehicle control. Not only did PpIX levels increase, but also PpIX distribution became more homogeneous after CPBN pretreatment. In summary, the use of non-toxic CPBN as a neoadjuvant prior to PDT is a combination approach with significant potential for translation into the clinic.

Date Published: 8 February 2017
PDF: 9 pages
Proc. SPIE 10047, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVI, 100470K (8 February 2017); doi: 10.1117/12.2256511

Published in SPIE Proceedings Vol. 10047:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XXVI
David H. Kessel; Tayyaba Hasan, Editor(s)